1. Field
One or more embodiments relate to a carbazole compound and an organo-electroluminescent device using the same, and more particularly, to a carbazole compound capable of forming a high-quality organic layer and an organo-electroluminescent device having excellent internal and external luminescence efficiency and high color purity using the carbazole compound.
2. Description of the Related Art
Organo-electroluminescent devices include a first electrode, a second electrode and at least one organic layer interposed between the first and second electrodes. The organic layer may be classified as vacuum deposited materials or solution coated materials depending on the method used to prepare the organic layer. The vacuum deposited materials may have a vapor pressure of greater than or equal to 10−6 torr at a temperature of less than or equal to 500° C. and may comprise a low molecular weight material having a molecular weight of less than or equal to 1200 Daltons. The solution-coated materials may be highly soluble in a solvent to facilitate preparation of a solution of the materials, and may include an aromatic or heterocyclic group.
Use of vacuum deposition processes in the manufacture of organo-electroluminescent devices may increase costs. When a shadow mask is used to manufacture pixels for displays producing natural colors, the pixels may not provide high resolution. On the other hand, when organo-electroluminescent devices are manufactured using a solution coating method such as inkjet printing, screen printing or spin coating, organic layers may be readily formed, which may reduce manufacturing costs. In addition, organo-electroluminescent devices manufactured using solution coating may have higher resolution than organo-electroluminescent devices manufactured using a shadow mask.
One drawback of solution coating methods is that the materials used in solution coatings have poorer thermal stability and lower color purity than those used in vacuum deposition. In addition, the materials used in solution coatings may crystallize, and the crystal size may be commensurate with a wavelength of visible light. Thus a white residue may form due to scattering of visible light by the crystals or pin holes may be formed, which may degrade desirable properties of the organic-electroluminescent devices.
Thus, there is still a need to develop an organo-electroluminescent device having low driving voltage, excellent luminescence brightness, high luminescence efficiency and high color purity. There further remains a need for developing an organic compound capable of forming an organic layer by solution coating for use in the organo-electroluminescent device, where the compound has excellent thermal stability and high color purity.